1. Field of the Invention
The present invention concerns means for positioning a workpiece within the operating area of a machining apparatus. In particular, the invention relates to a multi-component assembly for adjustably and repeatably locating a workpiece at a precise location relative to a machine tool.
2. Description of the Prior Art
As the level of technology has increased, the requirement for more complicated, detailed and precision made parts has likewise increased. To produce such parts, a machining technology has evolved termed "wire electrical discharge machining" or wire EDM. This technology permits the machining of complicated geometric shapes from particularly hard and difficult to cut electrically conductive materials.
A problem with such machines, however, is that only one part at a time can be machined. Also, the cutting speed of a wire EDM machine is relatively slow. These disadvantages, plus the high cost of wire EDM machines, induce a manufacturer to enhance the effectiveness of the machine as much as possible.
As a partial resolution to the above problems, operators are learning to pre-rig a workpiece within a clamping assembly while the machine is simultaneously operating on another workpiece. In this way, the workpiece changeover time is significantly reduced and the efficiency of the machine is greatly enhanced.
A difficulty with the above procedure is being able to quickly and precisely locate the workpiece relative to the wire or machine tool on a consistent and repetitive basis. This difficulty has been addressed in U.S. Pat. Nos. 4,656,326 and 4,786,776. Each of these patents describe a complicated assembly of numerous parts which all fit together from the surface of the machine tool table. The patents show the use of multiple plates, bridge parts, large reference blocks, miscellaneous braces and slotted clamps. Not only are the above parts cumbersome and difficult to adjust, if just one of the many parts becomes misaligned or in some way distorted, each of the successive parts becomes exaggerated in misalignment. Further, such systems are expensive and time-consuming to use.